(function(){
    self.onmessage = function(e){
      transAudioData.transcode(e.data)
    }
  
    let transAudioData = {
      transcode(audioData) {
        let output = transAudioData.to16kHz(audioData)
        output = transAudioData.to16BitPCM(output)
        output = Array.from(new Uint8Array(output.buffer))
        self.postMessage(output)
        // return output
      },
      to16kHz(audioData) {
        var data = new Float32Array(audioData)
        var fitCount = Math.round(data.length * (16000 / 44100))
        var newData = new Float32Array(fitCount)
        var springFactor = (data.length - 1) / (fitCount - 1)
        newData[0] = data[0]
        for (let i = 1; i < fitCount - 1; i++) {
          var tmp = i * springFactor
          var before = Math.floor(tmp).toFixed()
          var after = Math.ceil(tmp).toFixed()
          var atPoint = tmp - before
          newData[i] = data[before] + (data[after] - data[before]) * atPoint
        }
        newData[fitCount - 1] = data[data.length - 1]
        return newData
      },
      to16BitPCM(input) {
        var dataLength = input.length * (16 / 8)
        var dataBuffer = new ArrayBuffer(dataLength)
        var dataView = new DataView(dataBuffer)
        var offset = 0
        for (var i = 0; i < input.length; i++, offset += 2) {
          var s = Math.max(-1, Math.min(1, input[i]))
          dataView.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true)
        }
        return dataView
      },
    }
  })()